Ammonia (NH3) as a fuel for the Solid Oxide Fuel Cell (SOFC) appears to be very attractive. SOFC systems fuelled with ammonia are relative simple compared with carbon containing fuelled systems, since no humidification of the fuel is necessary to prevent carbon deposition. Also, the endothermic NH3 cracking reaction consumes part of the heat produced by the fuel cell, by which less cathode flow is required for cooling of the stack compared with H2 fuelled systems. Therefore the systems for a NH3 fuelled SOFC will have relatively low parasitic power losses and smaller heat exchangers.
U.S. 2008248353 for instance describes an energy conversion system comprising ammonia for fuelling a SOFC stack to generate electricity and a hydrogen-rich tailgas. In the SOFC stack, ammonia is cracked to hydrogen and nitrogen. Ammonia is stored in a metal halide complex and is released therefrom as gaseous ammonia by waste heat from the SOFC. A heat exchanger is positioned across the SOFC cathode such that incoming air is tempered by the cathode exhaust air. In a two-stage energy conversion system, the hydrogen-rich tailgas from the SOFC is supplied as fuel to a secondary energy conversion device which may be, for example, an internal combustion engine or a gas turbine engine which may operate, for example, either a generator for generating additional electricity or a vehicle for motive power, or a second fuel cell stack.
U.S. 2007207351 describes an electric power generating unit comprising (i) an ammonia storage device in the form of a container comprising an ammonia absorbing and releasing salt of the general formula: Ma(NH3)nXz, wherein M is one or more cations selected from alkali metals, alkaline earth metals, and transition metals such as Li, K, Mg, Ca, V, Cr, Mn, Fe, Co, Ni, Cu or Zn, X is one or more anions selected from fluoride, chloride, bromide, iodide, nitrate, thiocyanate, sulphate, molybdate, phosphate, and chlorate ions, a is the number of cations per salt molecule, Z is the number of anions per salt molecule, and n is the coordination number of 2 to 12, (ii) means for heating said container and ammonia absorbing and releasing salt for releasing ammonia gas and (iiia) a fuel cell for converting ammonia directly into electric power; or (iiib1) a reactor for dissociating ammonia into hydrogen and nitrogen and (iiib2) a fuel cell for converting hydrogen into electric power is useful for large stationary energy producing facilities, but also for use for is useful for large stationary energy producing facilities, but also for use for small rechargeable and/or replaceable power supply units for micro-fabricated or miniaturized ammonia decomposition reactors for use in mobile units and portable devices may be used for large energy producing facilities, and by use of small rechargeable and/or replaceable ammonia storage decomposition reactors, it is also possible to provide energy for mobile units and portable devices.
U.S. 2003219371 describes a method and apparatus for generating energy from a composition comprising urea and water are described. The method in one embodiment includes: (a) reacting the urea with water to form ammonia; and (b) oxidizing the ammonia formed in step (a) to form water and nitrogen generating energy. The apparatus in one embodiment contains: (a) a first container for providing the composition; (b) a second container for reacting the urea with water to form ammonia, wherein the second container is connected to the first container by means for delivering the composition from the first container to the second container; (c) a third container for providing ammonia, wherein the third container is connected to the second container by means for delivering ammonia from the third container to the second container; and (d) a fourth container for oxidizing ammonia to form water and nitrogen generating energy, wherein the fourth container is connected to the second container by means for delivering ammonia from the second container to the fourth container. The method and apparatus are used to generate energy for use in stationary and mobile applications.
Dekker et al describe in a paper entitled “Highly efficient conversion of ammonia in electricity by solid oxide fuel cells” (6th European Solid Oxide Fuel Cell Forum, 1 Jan. 2005, p 1524-1534) that SOFC systems fuelled with ammonia are relative simple compared with carbon containing fuelled systems, since no humldiflcation of the fuel is necessary to prevent carbon deposition. Also, the endothermic NH cracking reaction consumes part of the heat produced by the fuel cell, by which less cathode flow Is required for cooling of the stack compared with H. fuelled systems. Therefore the system Tor a NH. fuelled SOFC will have relatively law parasitic power losses end smaller heat exchangers.
WO2009091959 describes methods for removal and disposal of ammonia from spent dialysate in a dialysis system. Ammonium ions present in spent dialysate are converted into gaseous ammonia by raising the pH of the spent dialysate solution in a first reactor. Gaseous ammonia diffuses through a semi-permeable hydrophobic membrane at the outlet of the first reactor and into a second reactor via a gas channel. The second reactor converts gaseous ammonia into an ammonium compound for easy disposal.
WO2005035444 describes an electro-catalyst for the oxidation of ammonia in alkaline media; the electrocatalyst being a noble metal co-deposited on a support with one or more other metals that are active to ammonia oxidation. In some embodiments, the support is platinum, gold, tantalum, or iridium. In some embodiments, the support has a layer of Raney metal deposited thereon prior to the deposition of the catalyst. Also described are electrodes having the electro-catalyst deposited thereon, ammonia electrolytic cells, ammonia fuel cells, ammonia sensors, and a method for removing ammonia contaminants from a contaminated effluent.